1. Field of the Invention
This invention relates to a terminal and a method of manufacturing a terminal which is used for connecting electric circuits.
2. Background
A pair of terminals including a male terminal and a female terminal are generally used for interconnecting electric circuits. FIG. 5 is a perspective view of an example of a male terminal M.
The male terminal M is formed by bending an electric conductive plate. Specifically, an electric contact portion a located at an end portion of the male terminal M is formed by bending the electric conductive plate inwardly. The electric contact portion a is received in a cylindrically or cubically shaped opening of the female terminal (not shown), and is electrically engaged by a spring member provided in the electric contact portion of the female terminal.
Conventionally, the contact surface of the electric contact portion of the terminal is metal-plated with a different type of a metal from the base material to prevent corrosion and improve electrical conduction, etc. An example of a method conventional metal-plating is disclosed in Japanese Patent Laid-Open No. Hei. 5-6790. In this method, a conductive plate is first plated and then bent into the shape of a male terminal by a punching or a pressing process. Further, according to another example, it is well-known to form the male terminal and then dip the male terminal into a plating liquid.
However, in the former method, when an electric contact portion of the male terminal is formed by pressing the conductive plate after it has been plated, there is a possibility that cracks may form in the plated surface of the electric contact portion. Thus, the reliability of the terminal is poor since cracks may develop along with corrosion. Furthermore, there is a fault that vain plating liquids are needed, because a metal-plated portion naturally remains on a scrap of the electric conductive plate after punching the male terminal.
On the other hand, in the latter method, the electric contact portion a of a male terminal M (shown in FIG. 5) is formed by a pressing operation in which the metal plate is inwardly folded resulting in the hardening of the electric contact portion a. However, with reference to FIG. 6, the plating liquid may become entrapped in the opening b as a result of being dipped in the liquid.
Namely, a preliminary treatment process (a grease-removing treatment a washing treatment an activating treatment the washing treatment the activating treatment the washing treatment and a pure-watering treatment) is done before a metal-plating treatment process, the male terminal M is metal-plated using a variety of solutions (e.g., an alkaline cleaner used in the grease-removing treatment, a dilute sulfuric acid used in the activating treatment and etc.) associated with the preliminary treatment process. The solutions (or a treatment solution of the metal-plating treatment process) may become entrapped in the opening b thereby gradually corroding the metal-plated layer or the base material (copper etc.) of the terminal.